Endwise adjustable forceps for lens implantation in eye

ABSTRACT

An intraocular lens implantation forceps, including first and second arms having handles and lens engagement blades; the blades extending generally longitudinally in laterally spaced relation and at opposite sides of a plane bisecting the forceps. The arms have primary and secondary arm sections extending between the handles and blades. The arms primary sections extend in cross-over relation to define a cross-over locus, when the blades are in open position; the secondary arm sections extending generally longitudinally in substantially parallel relation and positioned such that when the blades are in the closed positions one secondary arm section extends at one side of the plane and the other secondary arm section extends at the other side of the plane, and when the blades are in the open positions the one secondary arm section extends at the other side of the plane and the other secondary arm section extends at the one side of the plane.

BACKGROUND OF THE INVENTION

This invention relates generally to intraocular lens implantation, andmore particularly concerns apparatus and method for achieving suchimplantation via a very small surgical incision in the corneo-sclerallimbus of the eye.

In the past, forceps have been used with blades that clamp the plasticlens for introducing it into the eye via a relatively wide wound orincision in the corneo-scleral limbus. A typical wound was required tohave a width of about 7-15 millimeters in order to pass the forcepblades and to allow spreading of the blades to release the plastic lensin the eye.

Problems encountered included laceration of the elastic silicon lens,and undesirable sudden release and rapid unfolding of the lens (asopposed to gentle release) causing injury to intraocular tissue, due toinability to separate the blades widely and gently. The usual wideincision is undesirable due to the amount of suturing required to closethe wound, and time required for such suturing, increased or undesirablylong convalescence time, increase in astigmatic complications,difficulty in preventing collapse of the intraocular chambers during theoperation, and increased risk of post-operative complications. Further,plastic lenses could and did at times become captured by the blades ofprior forceps, requiring dangerous instrumentation to release the lensfrom the grasp of such forceps. The invention of U.S. Pat. No. 4,513,957represents one approach to the solution of this problem.

SUMMARY OF THE INVENTION

It is a major object of the invention to provide improved method andapparatus, overcoming the above problems and difficulties. Basically theinvention permits wide separation of the blades, adjusted bladepositioning in the eye, and controlled release of the folded lens withinthe eye, while motion is transmitted to the blades via a very narrowincision.

The apparatus is usable for implanting a plastic lens into the eye lenszone from which a natural but cataractous lens has just been removed (orremoved in the past) as via a narrow surgical incision in thecorneo-scleral limbus, and while using a forceps having bladesprojecting from or beyond arm portions typically defining a cross-overlocus in blade open positions, the apparatus movable endwise in thenarrow slit to enable precise positioning of the lens prior to itsrelease by the blades. Such apparatus comprises

a) first and second arms, the first arm having a first handle and afirst lens engagement blade spaced from the first handle, the second armhaving a second handle and a second lens engagement blade spaced fromthe second handle, the blades extending generally longitudinally inlaterally spaced relation and at opposite side of plane bisecting theforceps,

b) the first arm having primary and secondary arm sections extendingbetween the first handle and first blade, the second arm having primaryand secondary arm sections extending between the second handle andsecond blade, the blades being movable by the handles and arm sectionsbetween closed and open positions relative to the lens, the arm primarysections extending in cross-over relation to define a cross-over locus,when the blades are in open position, and

c) the secondary arm sections extending generally longitudinally insubstantially parallel relation and positioned such that when the bladesare in their closed positions one secondary arm section extends at oneside of the plane bisecting the forceps, and the other secondary armsection extends at the other side of that plane, and when the blades arein the open positions the one secondary arm section extends at the otherside of the plane and the other secondary arm section extends at the oneside of the plane.

Typically, the secondary arm sections have lengths greater than theirmaximum lateral separation, to allow movement thereof back and forth inan incision or wound in the eye corneo-scleral limbus via which theblades and lens are inserted into the eye.

Another object includes providing a first blade as referred to whichremains at said one side of the bisecting plane as the blades are movedbetween said closed and open positions, and the second blade remains atsaid other side of said plane as the blades are moved between saidclosed and open positions. Also, the first handle typically remains atsaid other side of said plane as the blades are moved between saidclosed and open positions, and the second handle remains at said oneside of said plane as the blades are moved between said closed and openpositions.

Yet another object is to provide secondary arm sections which havesubstantially equal lateral separation in said closed and open positionsof the blades. In this regard, the primary arm sections are everywherelaterally separated when the blades are in closed position; also theprimary arm sections extend at opposite angles relative to said plane,and they have lengths substantially less than the longitudinal lengthsof said secondary arm sections.

A further object is to provide blades which have lens gripping tongsprojecting toward said plane, to grip opposite sections of the foldedlens, the tongs defining pivots about which the folded lens may pivotduring unfolding release of the lens as the blades are moved from closedto open positions. In this regard, the tongs are typically located attips of the blades remote from the arm cross-over locus. For example,the tongs may be attached to end portions of the blades, or may belocated or attached closer to the root ends of the blades, to allowpreferential expansion and escape of the lens implant in a mannerdesired by the surgeon, and as will be seen. The gripped lens is folded,and the tongs pushed into local portions of the folded blades to enablepivoting of the lens as it is controllably released by blade separation,with the tongs continuing to controllably locate the lens as it unfoldsor expands.

Finally, the improved forceps is not only useful as an intraocular lensholder, but also as a utility forceps, capable of passing through asmall puncture wound to insert a lens implant, or grasp an intraocularforeign body or a tissue for its removal or better positioning--allthrough the small puncture wound. The forceps is therefore usable forother purposes where maximum maneuvering within a small slit or wound isdesired, for example.

These and other objects and advantages of the invention, as well as thedetails of an illustrative embodiment, will be more fully understoodfrom the following specification and drawings, in which:

DRAWING DESCRIPTION

FIG. 1 is a side view of a cataractous opaque lens;

FIG. 2 is a side view of the cataractous opaque lens within the lenscapsule in the eye;

FIG. 3 is a side view of the anterior lens capsule after removal of theopaque cataract lens and the central portion of the anterior capsule;

FIG. 4 is a front view of the cataractous lens as seen in FIG. 1,showing zonula fibers holding the capsule;

FIG. 5 is a front view showing the location of a surgical 1 to 3 mmincision in the coroscleral tissue, outwardly from the limbus;

FIG. 6 is a view showing the forceps of the invention in folded lensgripping position;

FIG. 7 is a view like FIG. 6, but showing the forceps in lens releaseposition;

FIGS. 8 and 9 are side elevations showing cut-outs in elongated sectionsof the forceps arms;

FIG. 9a shows the FIGS. 8 and 9 arms in assembled relation;

FIGS. 10 and 11 are side elevations showing progressive tilting orextraction of a lens during its release by separating blades;

FIGS. 12 and 13 are side and end views of arm sections that extend in aconvex-convex sided wound during lens insertion into the eye;

FIGS. 14 and 15 are side and end views of arm sections that extend in aconvex-convex sided wound, as during lens release in the eye;

FIGS. 16, 18 and 20 are views of an instrument during progressive lensrelease;

FIGS. 17, 19 and 21 are end views of the instrument arms in FIGS. 16, 18and 20, respectively; and

FIG. 18a is a modified form of FIG. 18.

DETAILED DESCRIPTION

Referring first to FIGS. 1 and 2, they show in side view, andschematically, a cataractous opaque lens 10, bounded peripherally byzonula fibers 11, and located between anterior and posterior portions12a and 12b of the lens capsula. The eye outline appears schematicallyat 13, and FIG. 17 is a section accurately showing corresponding parts,as well as other parts, of the eye. FIG. 3 shows the capsule void 12cafter removal of the cataractous lens tissue. FIG. 4 is a front view ofthe lens 10 seen in side view in FIG. 1.

FIG. 5 is a schematic frontal view of the eye, showing a narrow (forexample about 3 mm wide) incision or puncture 14 in the corneoscleraltissue 15, at a short distance (as for example about 2 mm) from thelimbus 16, the latter designating the merging of light (sclera) and dark(iris periphery) zones of the eye. The present invention makes possiblethe use of such a narrow, i.e. short, puncture wound, as opposed to theprior very wide incision, indicated by broken lines 14a, which wasnecessary in order to implant a plastic or silicon lens into the capsula12. Such a wide (typically 15-18 mm) incision requires much moresuturing than is required for the short incision or puncture wound 14,and requires a longer convalescence period, with increased risk ofpost-operative complications. The cataractous lens is more recentlyremoved by phacoemulsification with ultrasonic vibration fragmentationand aspiration via the puncture 14, leaving jagged anterior "leaves" orserrations 17 in the anterior capsula portion 12a; the posterior capsulaportion 12b remains clear. Anterior capsulatomy removes the centralanterior capsula, leaving space indicated at 12c in FIG. 3.

Referring to FIGS. 6 and 7, the forceps of the present invention includefirst and second arms 22 and 23, the first arm having a first handle 22aand a first lens engagement blade 22b spaced endwise forwardly fromhandle 22a. The second arm 23 is a mirror image of arm 22, relative to alongitudinally forwardly extending central plane 24 bisecting theforceps. Second arm 23 has a second handle 23a and a second lensengaging blade 23b spaced endwise forwardly of handle 23a. Handles 22aand 23a are laterally spaced apart, and movable from lens grip positionsas during lens insertion through slit 14 (puncture wound) incorneoscleral tissue 15; i.e. from position as shown in FIG. 6 toposition as shown in FIG. 7. At the same time, the blades are relativelymovable laterally from FIG. 6 to FIG. 7 position, i.e. from positiongripping folded plastic or silicon lens 25 to position releasing thatlens (in FIG. 7) for controlled unfolding and implantation in selectedposition (in longitudinal direction 50) in the eye, without widening thenarrow slit. Note that blades 22b and 23b extend generallylongitudinally in laterally spaced relation relative to and at oppositesides of central plane 24 that bisects the forceps. As will be seen, theblades may taper forwardly as seen in FIG. 12, and may have bluntopposed tongs 22d and 23d at the blade tips, that slightly push into thefolded lens to provide pivot points for lens pivoting to enablecontrolled release and expansion of the lens while it remains positionedendwise relative to the blades, for precision positioning in the eye.

The arm 22 also has primary and secondary arm sections 22e and 22fextending between the handle 22a and blade 22b; and the second armlikewise has primary and secondary arm sections 23e and 23f extendingbetween handle 23a and blade 23f. Sections 22e and 23e extend incross-over relation, as at 28, to define a cross-over locus when theblades are in open position; however, when the blades are moved togetherto grip the folded lens, i.e. as by allowing the handles to spring apartin directions 29a and 29b, the cross-over locus 28 disappears, whereas across-over locus is formed at 128 spaced rightwardly of sections 221 and23e. See FIG. 6. Note that, in general, the blades are movable by fingerpressure on the handles 22a and 23a, as shown, to move the bladesbetween open and closed positions, relative to the lens. In FIG. 7, thelens is shown as rotating and expanding from folded position towardunfolded position. Lens haptics appear at 25a and 25b. The handles aretypically connected by a resiliently deflectable metal spring loop,indicated at 60.

In accordance with an important aspect of the invention, the secondaryarm sections 22f and 23f extend generally longitudinally insubstantially parallel relation and positioned such that when the bladesare in said closed positions one secondary arm section extends at oneside of plane 24 and the other secondary arm section extends at theother side of said plane, and when the blades are in said open positionssaid one secondary arm section extends at said other side of said planeand said other secondary arm section extends at said one side of saidplane. Typically, the secondary arm sections 22f and 23f havelongitudinal length greater than their maximum lateral separation toallow movement thereof back and forth in an incision wound in the eyecorneo-scleral limbus via which the blades and lens are inserted intothe eye.

During handle movement to move arm sections 22f and 23f between FIGS. 6and 7 positions, the first blade 22b remains at the one side of theplane as the blades are moved between the closed and open positions, andthe second blade remains at the other side of the plane as the bladesare moved between the closed and open positions. In addition, the firsthandle 22a remains at the other side of the plane as the blades aremoved between the closed and open positions, and the second handle 23aremains at the one side of the plane as the blades are moved between theclosed and open positions.

It should be noted that the arms, handles and blades remain in FIG. 6position during lens insertion into the eye, and while the lens isaccurately positioned, longitudinally, in direction 50, as enabled bylongitudinal elongation of arm sections 22f and 23f, which sections canmove back and forth in the wound or slit without widening theirseparation, even during eventual lens release while the blades are heldagainst further longitudinal movement. In this regard, note that inFIGS. 6 and 7, the arm secondary sections 22f and 23f have substantiallyequal lateral separation in the closed and open positions of the bladesand they move closer together during blade movement between FIG. 6 andFIG. 7 position. Thus, the slit or wound can be kept minimized, and thearm sections 22f and 23f can be moved back and forth, and rotated, inthe wound, to enable very accurate lens and haptics positioning. Aspreviously stated, and as shown in FIG. 7, the arm primary sections 22eand 23e are everywhere laterally separated when the blades are in closedposition. Note that sections 22e and 23e in FIG. 7 extend at oppositeangles α and -α, relative to plane 24; also, sections 22e and 23e havelengths substantially less than the longitudinal lengths of arm sections22f and 23f.

In FIG. 6 the arm cross-over (cross-fixation) point or locus 128 definedby arm sections 22i and 23i is very close to the blades, whereby theblades are held near one another with the folded lens therebetween, forinsertion through the narrow puncture. Once insertion is completed, andthe blades adjusted longitudinally to position the lens, the blades areallowed to slowly separate as by slow increase of manual pressure on thehandles 22a and 23a of the forceps. This allows ultimate wide separationof the blades, to between 4 to 6 mm, as seen in FIG. 7 withoutrestriction imposition by the small narrow slit or puncture. The widthof the puncture is less than about 3 mm. The blades remain approximatelyparallel during their excursions.

Note that two different longitudinally spaced cross-over loci, at 24 and128 are provided, one being operative as in FIG. 6, and the other as inFIG. 7.

FIG. 8 shows an arm 22 in side elevation, with elements labeled as inFIGS. 6 and 7. Note the cut-out 22gg in arm section 22ff, at the bottomthereof. FIG. 9 is like FIG. 8, but the cut-out 23gg in section 23ff isat the top of that section, of arm 23. The arm handles 22a and 23aextend at an upward angle β, relative to the length directions of 22ffand 23ff. Each blade has a blunt tang or tong at its tip to press intothe opposite sides of the folded lens, and act as a lens pivot duringlens release, as the blades are separated to FIG. 7 position. See tongs22d and 23d, as in FIG. 12. FIG. 9a shows the FIGS. 8 and 9 arms andblades in side-by-side position, as in use, whereas FIGS. 8 and 9 showthem separated for illustration. FIGS. 10 and 11 show such progressivefolded lens 25 pivoting, about the axis defined by the two lens engagingopposed tangs or tongs, as the blades separate, allowing controlledrelease, unfolding and positioning of the lens. In FIG. 11, the lensrotates slowly counterclockwise, under control, during release. If thepivots or tongs are not at the blade tips, but near the blade ends as inFIG. 18a, see 22d' and 23d', the lens rotates clockwise during release.

FIGS. 12 and 13 show the positions of the wedge shaped cross-section armsections 22f and 23f, between concave walls 14a and 14b of a slit 14, asthe sections begin to move from FIG. 6 position toward FIG. 7 position.FIGS. 14 and 15 show the positioning of the sections 22f and 23f betweenconcave walls 14a and 14b, in FIG. 7 positions of the arms, the wedgeshaped arm sections fitting the seat wall shapes in FIG. 15.

FIG. 16 is another view of blades and arms, 122f, 123f, 122b and 123b,corresponding to these elements seen in FIG. 6. Note that in FIG. 16 theblades are closed toward one another so that tongs 122d and 123d touch.The arms, in wedge shaped cross-section appear in FIG. 17, relative toslit or puncture walls, arm 122f being to the right of arm 123f. In FIG.18 the arms now appear superimposed as the blades separate somewhat, afolded lens 125 now held between the blades, with tongs 122d and 123dnear the blade tips pushing into the lens sides. FIG. 19 shows superposition of the arms in the wound or slit enabling arm movement back andforth in direction 140, corresponding to 40 in FIGS. 6 and 7, as well asarm rotation in the wound. In the modification of FIG. 18a, like FIG.18, the tongs 122d' and 123d' are near the blade roots, whereby the lensis released to rotate oppositely to lens rotation in FIG. 18, uponrelease. In FIG. 20, corresponding to FIG. 7, the arm 122f is now spreadto the left of arm 123f, and the blades are increasingly separated toallow lens 125 pivoting and release.

In use, the folded lens is moved into the capsulorhexis and placed inthe neutral position. The leading edge of the lens is placed beneath theanterior capsule. The haptics are readily rotated posteriorly into thebag. This assists in the implantation of the lens before separating theblades. With the blades separating, the lagging edge of the lens escapesfirst while the leading edge is held 30-60 seconds longer. This producesa very controlled non-explosive lens implant release. The lagging edgeof the optic advantageously moves posteriorly into the bag, its hapticalso expands slowly. The remaining portion of the lens that is stillgrasped and is held posterior to the anterior capsule in the neutralposition. The haptics are readily rotated posteriorly into the bag allof which assists in the implantation of the lens before spreading theblades. The final release of the leading portion of the lens is gentleand is especially achievable with 75% of the lens compression alreadydissipated.

Because the shafts are superimposed, slightly off center, theadvantageous illusion of a single, narrow shaft persists, whereby theuser is not confused. See FIG. 13. This is of further advantage when thetransitional area of the distal shaft is bent abruptly in an area notover 2 mm long. The overall length of the forceps lies only in theanterior chamber and can be reduced to (6+2)=8 mm. In this manner thespreading transitional area of the shaft and blade will not occupy anyspace in the corneal scleral or limbal wound. If the shafts are longenough so as to not only extend out of the corneal scleral wound, andalso long enough to extend out of the wound of the scleral tunnel, thenone folding forceps will satisfy the needs for both short and lengthyscleral wounds. The parallel shafts 22f and 23f will remain in theperimeters of the corneal scleral wound, using 6 mm long blades.

The present forceps is made to achieve a non-explosive and non-suddenrelease of a compressed, folded silica lens implant, after having passedthrough a narrow, corneo-scleral tunnel wound or slit without limitationof the spreading of the blades or spreading of the transitional, distalshafts (see FIGS. 8 and 9). Sufficient lateral strength of the debulkedshafts (see FIGS. 8 and 9) is achieved while they still appearaesthetically narrow, strong, maneuverable, and safe. Apexed, horizontaldesign of the shafts is provided as shown.

Additional advantages imparted to the lens grasping blades, and theirrelease of a folded lens through a capsulorhexis and into theintracapsular lens bad, are enabled through provision of convergence ortaper of the blades, and tong tips of the blades. This permits theblades to control lens escape earlier (sooner) and gradually andnon-explosively, with less spread of the blades and shaft. Thus,controlled manipulation through a smaller wound is afforded.

Also significant are the crossing shafts with their transitional, distaland proximal angled extents connected to the blades and to the handles,such angled extents (as at 22e and 23e, and 22i and 23i) permitted tocross over in almost parallel arrangement. Excursion is conveyed over agreater distance; and thus the same instrument can be used for a limbalwound as well as in a wound 4 to 5 mm posterior to the limbus, in a verynarrow tunnel 2.2 to 2.3 mm wide.

In summary, the instrument penetrates through long and short, narrowcorneo-sclera wounds. The transitional, distal shafts and the blades donot impinge on the corneo-scleral wound, which would limit the lateralexcursions of the blades. The lens grasping mechanism permits earlierand non-explosive release of the compressed silicon lens implant. Theaesthetic appearance of the instrument enhances maneuverability of theforceps, in a smaller wound. Instrument arms provide strength withbroad, horizontal, apexed (wedge shaped cross-section arms) lateralsides sliding past one another on separation of the blades. It enhancessafety over conventional, non-vertical shafts which let fluid escapefrom the eye with a danger of collapse of the anterior chamber on theinstrument or during release of the lens implant.

I claim:
 1. An improved intraocular lens implantation forceps,comprising:a) first and second arms, the first arm having a first handleand a first lens engagement blade spaced from the first handle, thesecond arm having a second handle and a second lens engagement bladespaced from the second handle, the blades extending generallylongitudinally in laterally spaced relation and at opposite sides of aplane bisecting the forceps, b) the first arm having a primary sectionand a secondary section, the primary and secondary arm sectionsextending between the first handle and first blade, the second armhaving a primary section and a secondary section, the primary andsecondary arm sections of the second arm extending between the secondhandle and second blade, the blades being movable by the handles and armsections between closed and open positions, the arm primary sectionsdefining a cross-over locus, when the blades are in said open position,c) the secondary arm sections extending generally longitudinally insubstantially parallel relation and positioned such that when the bladesare in said closed position one secondary arm section extends at oneside of said plane and the other secondary arm section extends at theother side of said plane, and when the blades are in said open positionssaid one secondary arm section extends at said other side of said planeand said other secondary arm section extends at said one side of saidplane.
 2. The forceps of claim 1 wherein the secondary arm sections havemaximum lateral separation, and longitudinal lengths greater than theirsaid maximum lateral separation to allow movement back and forth in anincision wound in the eye corneo-scleral limbus via which the blades andlens are inserted into the eye.
 3. The forceps of claim 2 wherein theprimary arm sections extend at opposite angles relative to said plane.4. The forceps of claim 2 wherein the primary arm sections have lengthssubstantially less than the longitudinal lengths of said secondary armsections.
 5. The forceps of claim 1 wherein said first blade remains atsaid one side of said plane as the blades are moved between said closedand open positions, and the second blade remains at said other side ofsaid plane as the blades are moved between said closed and openpositions.
 6. The forceps of claim 5 wherein said first handle remainsat said other side of said plane as the blades are moved between saidclosed and open positions, and the second handle remains at said oneside of said plane as the blades are moved between said closed and openpositions.
 7. The forceps of claim 1 wherein said arm secondary sectionshave lateral separation in each of said closed and open positions of theblades, said lateral separations being equal.
 8. The forceps of claim 7wherein the primary arm sections are laterally separated when the bladesare in closed position.
 9. The forceps of claim 1 wherein said bladeshave lens gripping tongs projecting toward said plane, to grip oppositesections of the folded lens, the tongs defining pivots about which thefolded lens may pivot during unfolding release of the lens as the bladesare moved from closed to open positions.
 10. The forceps of claim 9wherein the blades have tips remote from said secondary arm sections,said tongs located at said tips.
 11. The forceps of claim 9 incombination with a folded plastic lens defining said opposite sectionswhich are gripped by said blades in said closed position, with saidtongs pushed into said respective opposite sections of said lens. 12.The forceps of claim 9 wherein said blades taper toward said plane indirections away from said secondary arm sections.
 13. The forceps ofclaim 9 wherein said tongs are located closer to root ends of the bladesthan to tips of the blades, said root ends and tips defined by theblades.
 14. The forceps of claim 1 in combination with a folded plasticlens gripped by said blades in said closed position thereof.
 15. Theforceps of claim 14 wherein said lens has folded sections, and hapticsrespectively connected to said sections and extending in a relativelyfolded state.
 16. The method of implanting in the eye an intraocularlens, and via a slit in the eye wall, that includes the steps:a)providing a forceps having first and second arms, the first arm having afirst handle and a first lens engagement blade spaced from the firsthandle, the second arm having a second handle and a second lensengagement blade spaced from the second handle, the blades extendinggenerally longitudinally in laterally spaced relation and at oppositesides of a plane bisecting the forceps, b) said first arm provided tohave a primary and a secondary arm section extending between the handleand the first blade, and said second arm provided to have a primary anda secondary arm section extending between the second handle and secondblade, the blades being movable by the handles and arm sections betweenclosed and open positions, the arm primary sections defining across-over locus, when the blades are in said open position, c) saidsecondary arm sections provided to extend generally longitudinally insubstantially parallel relation and positioned such that when the bladesare in said closed position one secondary arm section extends at oneside of said plane and the other secondary arm section extends at theother side of said plane, and when the blades are in said open positionssaid one secondary arm section extends at said other side of said planeand said other secondary arm section extends at said one side of saidplane.
 17. The method of claim 16 including adjusting said forcepssecondary arm sections lengthwise in said eye wall slit whilemaintaining said primary and secondary arm sections in predeterminedspaced relation to said blades in predetermined spaced relation.
 18. Themethod of claim 16 wherein the arms have additional sections between theblades and said arm primary and secondary sections, and including thestep of maintaining said additional arm sections in cross-over relationwhen the blades are in said closed position.
 19. An improved forceps,comprising, in combination:a) first and second arms, the first armhaving a first handle and a first lens engagement blade spaced from thefirst handle, the second arm having a second handle and a second lensengagement blade spaced from the second handle, the blades extendinggenerally longitudinally in laterally spaced relation and at oppositesides of a plane bisecting the forceps, b) the first arm having primaryand secondary arm sections extending between the first handle and firstblade, the second arm having primary and secondary arm sectionsextending between the second handle and second blade, the blades beingmovable by the handles and arm sections between closed and openpositions, the arm primary sections extending in cross-over relation todefine a cross-over locus, when the blades are in said open position, c)the secondary arm sections extending generally longitudinally insubstantially parallel relation and positioned such that when the bladesare in said closed position one secondary arm section extends at oneside of said plane and the other secondary arm section extends at theother side of said plane, and when the blades are in said open positionsaid one secondary arm section extends at said other side of said planeand said other secondary arm section extends at said one side of saidplane, d) and lens gripping protrusions on the blades to grip walls of afolded lens and allow lens rotation during blade separation and lensrelease.